A194535 Number of lower triangles of an n X n 0..3 array with new values introduced in row major order 0..3 and no element equal to more than one horizontal or vertical neighbor

1, 4, 116, 16556, 7721920, 11525456507, 54979732214116, 838387866908847478, 40866499579695484000499, 6367568042830726931523028453, 3171485572844765112503023656979959

Offset

1,2

Comments

Column 3 of A194540

Links

R. H. Hardin, Table of n, a(n) for n = 1..12

Example

Some solutions for 3X3
..0......0......0......0......0......0......0......0......0......0......0
..1.2....1.1....1.2....1.2....1.1....1.2....1.2....1.2....1.0....1.2....1.1
..3.3.0..0.0.2..2.3.1..0.3.0..2.0.1..3.2.1..0.3.1..2.1.3..2.1.2..2.0.1..2.2.1

Crossrefs

Sequence in context: A206689 A198080 A272158 * A030255 A146508 A365450

Adjacent sequences: A194532 A194533 A194534 * A194536 A194537 A194538

Keyword

nonn

Author

R. H. Hardin Aug 28 2011

Status

approved